# Electrical Power Question

I am trying to compare watts exiting the battery vs watts being consumed by the bulb.

I have set up a test circuit shown below.

Should not A-B watts match C-D watts??

Sorry for such a basic question...I'm learning here...

• If A-B watts did match C-D watts, then that would mean that $R_1$ was 0 Ω, or that the voltage across the resistor is 0 V and/or that the current through the resistor is 0 A. Oct 30, 2018 at 10:59
• And this is theoretical. In a real circuit, everything has resistance - even the wires. So there is power loss in every single piece. Oct 30, 2018 at 12:12

$$P_{battery} = -(P_{resistor} + P_{lamp})$$
What you are ignoring is the power consumed by $$\R_1\$$.
$$P_{R_1} = (V_A - V_C)\ \times \ I = (6.15V - 1.434V) \times 0.335A = 1.58W$$